NifiApplication · Apache
CVE-2026-54665
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedApache NiFi 0.0.1 through 2.9.0 support building qualified URLs from one of several HTTP request headers that provide an alternative to the standard Host header without validating the values provided. Apache NiFi 1.6.0 introduced a configurable application property to restrict values provided in the HTTP Host header, but did not apply the validation to alternative Proxy and Forwarded headers. The absence of proxy host header validation allowed a client to instruct Apache NiFi web services to construct invalid qualified URLs for redirection or data references. Upgrading to Apache NiFi 2.10.0 is the recommended mitigation, which implements validation for the X-ProxyHost and X-Forwarded-Host HTTP request headers based on the nifi.web.proxy.host property. Enabling header validation requires configuring the application with HTTPS. Reverse proxy servers in front of Apache NiFi are responsible for filtering input request headers and providing allowed values to the application.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceApache NiFi fails to validate X-ProxyHost and X-Forwarded-Host HTTP headers when constructing qualified URLs, allowing attackers to manipulate redirection and data reference paths through unsanitized input. While version 1.6.0 added nifi.web.proxy.host validation for the standard Host header, this protection was not extended to alternative proxy headers, enabling HTTP Request Smuggling-like attacks.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
NifiApplication
>= 0.0.1, < 2.10.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed NiFi versionLocate the NiFi installation and check the version. In the NiFi UI, go to the Help > About page. Alternatively, check the nifi-version file in the NiFi root directory or the nar manifest files in the lib folder.Affected if The installed version is lower than 2.10.0 (any version from 0.0.1 through 2.9.x is affected).
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Verify nifi.web.proxy.host configurationOpen the nifi.properties file (typically in the conf directory) and search for the property nifi.web.proxy.host. Check if it is configured with a whitelist of allowed host values.Affected if The property is either unset or does not include values that properly restrict all proxy headers (the standard Host header may be validated but X-ProxyHost and X-Forwarded-Host are not).
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Identify if NiFi is exposed behind a reverse proxyReview the network configuration and proxy setup. Check if a web server (Apache HTTP Server, Nginx, or similar) sits in front of NiFi and forwards requests using X-ProxyHost or X-Forwarded-Host headers.Affected if A reverse proxy is configured to pass through X-ProxyHost or X-Forwarded-Host headers to NiFi without filtering them.
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Inspect HTTP response headers for header reflectionSend a test request to NiFi with a crafted X-ProxyHost or X-Forwarded-Host header (for example: X-Forwarded-Host: attacker.com) and observe if the response reflects this value in Location headers or generated URLs.Affected if The response includes the attacker-controlled header value in qualified URLs or redirection targets, indicating the headers are not sanitized.
You are affected if NiFi version is below 2.10.0 AND the application uses proxy headers (X-ProxyHost/X-Forwarded-Host) that are not filtered by a reverse proxy or restricted via configuration.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped2.10.0
Upgrade to Apache NiFi 2.10.0, configure HTTPS, and set the nifi.web.proxy.host property to whitelist allowed values. Ensure any reverse proxy in front of NiFi filters these headers before forwarding requests.
Apache NiFi 2.10.0
- Upgrade Apache NiFi to version 2.10.0
- If using a reverse proxy, configure the nifi.web.proxy.host property with allowed host values
- Ensure Apache NiFi is configured to use HTTPS (required for enabling header validation)
- Configure the reverse proxy in front of NiFi to filter and sanitize X-ProxyHost and X-Forwarded-Host headers, passing only allowed values
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Nifi
Scoped from the published advisory
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-54665 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-54665 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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